This invention relates to the novel processes for the preparation of 9,11-epoxy steroid compounds, especially those of the 20-spiroxane series and their analogs, novel intermediates useful in the preparation of steroid compounds, and processes for the preparation of such novel intermediates. Most particularly, the invention is directed to novel and advantageous methods for the preparation of methyl hydrogen 9,11α-epoxy-17α-hydroxy-3-oxopregn-4-ene-7α,21-dicarboxylate, γ-lactone (also referred to as eplerenone or epoxymexrenone).
Methods for the preparation of 20-spiroxane series compounds are described in U.S. Pat. No. 4,559,332. The compounds produced in accordance with the process of the '332 patent have an open oxygen containing ring E of the general formula:
in which
-A-A- represents the group —CH2—CH2— or —CH═CH—;
R1 represents an α-oriented lower alkoxycarbonyl or hydroxycarbonyl radical;
—B—B— represents the group —CH2—CH2— or an α- or β-oriented group;

R6 and R7 being hydrogen;
X represents two hydrogen atoms or oxo;
Y1 and Y2 together represent the oxygen bridge —O—, or
Y1 represents hydroxy, and
Y2 represents hydroxy, lower alkoxy or, if X represents H2, also lower alkanoyloxy;
and salts of such compounds in which X represents oxo and Y2 represents hydroxy, that is to say of corresponding 17β-hydroxy-21-carboxylic acids.
U.S. Pat. No. 4,559,332 describes a number of methods for the preparation of epoxymexrenone and related compounds of Formula IA. The advent of new and expanded clinical uses for epoxymexrenone create a need for improved processes for the manufacture of this and other related steroids.